1. Technical Field
This application relates to electronic equipment, and, in particular, to radio-frequency interference (RFI) and/or electromagnetic interference (EMI) shielding in electronic equipment.
2. Discussion of Related Art
Electronic systems or modules can typically include one or more printed circuit boards (PCBs) populated with electronic circuits and devices. The PCB(s) can be contained within a housing which can have one or more covers which mate together to enclose the PCB(s). Similarly, one or more of the PCB(s) can mate with one or more of the covers of the housing. In some electronic systems or modules, it is important that the internal electronic circuitry be shielded from RFI and EMI, both to prevent RFI and/or EMI in the external environment from interfering with the internal electronic circuitry and to prevent the electronic systems or modules from emitting signals into the external environment.
Typically, to prevent RFI and/or EMI, the mating covers of the housing and/or the mating covers and PCB(s) of the system are made of or coated with a conductive material. When the covers are mated together or when the PCB(s) and cover(s) are mated together, an electrical gasket, which can also include a conductive material, can be interposed between them to provide an electrical seal. Also, one or more shield devices can be installed in the assembly in electrical contact with the housing to shield the internal electronic circuitry. As a result, the circuitry can be completely enclosed by conductive material, which can be connected to the electrical ground of the system. This results in a complete shield against RFI and EMI.
Shields are typically fabricated using a conductive material such as metal or a plastic which absorbs and/or reflects electromagnetic radiation. In some applications, the absorptive and conductive plastic shield is preferred over the purely conductive, e.g., metallic, shield. In order to implement electrical contact between the shield and the housing, a soft conductive gasket can be over-molded to the shield. However, in order to over-mold the soft conductive gasket in applications in which the plastic shield is used, a high-temperature plastic material must be used as the shield material instead of a low-temperature plastic, which results in higher cost.